Chapter 9. Feeding Seven Billion Well: Moving Down the Food Chain

One of the questions I am most often asked on a speaking tour is, “How many people can the earth support?” I answer with another question: “At what level of food consumption?” At the U.S. level of 800 kilograms per person per year for food and feed, the 2-billion-ton annual world harvest of grain would support 2.5 billion people. At the Italian level of consumption of close to 400 kilograms per year, the current harvest would support 5 billion people. At the nearly 200 kilograms of grain consumed per year by the average Indian, it would support a population of 10 billion. 58

In every society where incomes rise, people move up the food chain, eating more animal protein as beef, pork, poultry, milk, eggs, and seafood. The mix of animal protein products varies with geography and culture, but the shift to more animal protein as purchasing power increases appears to be universal.

As consumption of livestock products, poultry, and farmed fish rises, grain use per person also rises. Of the roughly 800 kilograms of grain consumed per person each year in the United States, about 100 kilograms is eaten directly as bread, pasta, and breakfast cereals. But the bulk of the grain is consumed indirectly in the form of livestock, poultry, and farmed fish. By contrast, in India, where people consume just under 200 kilograms of grain per year, or roughly a pound per day, nearly all grain is eaten directly to satisfy basic food energy needs. Little is available for conversion into livestock products. 59

Of the three countries just cited, life expectancy is highest in Italy even though U.S. expenditures on medical care per person are much higher. Those who live very low on the food chain or very high on the food chain do not live as long as those in an intermediate position. The Mediterranean diet includes meats, cheeses, and seafood, but in moderation. Nutritionally, this is the healthiest way to eat. 60

What this means is that those living high on the food chain, such as the average American or Canadian, can consume less grain and improve health at the same time. For those who live in low-income countries like India, where diets are dominated by a starchy staple such as rice, sometimes supplying 60 percent or more of total caloric intake, eating more animal products can improve health and raise life expectancy. 61

In addition to having the affluent sector move down the food chain by consuming fewer livestock products, the world is turning to the more grain-efficient forms of animal protein. Together these two steps have helped hold the share of the world grain harvest used for feed constant at roughly 38 percent for the last two decades. 62

It is widely assumed that moving from animal protein to high-quality proteins from plant sources, such as beans or tofu made from soybeans, is more land-efficient. But this is not always the case. For example, as noted earlier, with poultry it takes just over 2 kilograms of grain to produce 1 kilogram of additional live weight. For catfish, it is less than 2 kilograms of grain per kilogram of weight gain. An acre of land in Iowa can thus produce 140 bushels of corn or 35 bushels of the much lower-yielding soybean. Feeding the corn to chickens or catfish can yield more high-quality protein than growing soybeans and consuming them directly, say as tofu. 63

It takes a good deal of land to produce soy protein, largely because plants require more metabolic energy to produce high-quality plant protein than to produce starch. But because poultry and catfish are so efficient at converting grain, eating them is more land- and water-efficient than eating soybeans is. 64

Some countries are moving down the food chain by turning to the more grain-efficient protein sources such as aquaculture. China, with its huge aquacultural output, may be the first country where the farmed fish harvest exceeds the wild fish catch. 65

With incomes now rising in densely populated Asia, other countries are following China’s lead. Among them are India, Thailand, and Viet Nam. Viet Nam, for example, devised a plan in 2001 of developing 700,000 hectares of land in the Mekong Delta for aquaculture, with the goal of producing 1.7 million tons of fish and shrimp by 2005. It now appears likely to exceed this goal. 66